Search

Background: African mahogany species (Khaya sp.) have been introduced to Brazil gaining increasing economic interest over the last years, as they produce high quality wood for industrial applications. To this date, however, the knowledge available on the genetic basis of African mahogany plantations in Brazil is limited, which has driven this study to examine the extent of genetic diversity and structure of three cultivated species (Khaya grandifoliola, Khaya senegalensis and Khaya ivorensis) and their prospects for forest breeding., Results: In total, 115 individuals were genotyped (48 of K. grandifoliola, 34 of K. senegalensis and 33 of K. ivorensis) for 3,330 filtered neutral loci obtained from genotyping-by-sequencing for the three species. The number of SNPs varied from 2,951 in K. ivorensis to 4,754 in K. senegalensis. Multiloci clustering, principal component analysis, Bayesian structure and network analyses showed a clear genetic separation among the three species. Structure analysis also showed internal structure within each species, highlighting genetic subgroups that could be sampled for selecting distinct genotypes for further breeding, although the genetic distances are moderate to low., Conclusion: In our study, SNP markers efficiently assessed the genomic diversity of African mahogany forest plantations in Brazil. Our genetic data clearly separated the three Khaya species. Moreover, pairwise estimates of genetic distances among individuals within each species showed considerable genetic divergence among individuals. By genotyping 115 pre-selected individuals with desirable growth traits, allowed us not only to recommend superior genotypes but also to identify genetically distinct individuals for use in breeding crosses., (© 2024. The Author(s).)

Microplants of Eucalyptus microcorys were produced through indirect organogenesis, and the interaction of plant growth regulators (PGRs) (TDZ-thidiazuron and NAA-α-naphthalene acetic acid), juvenile tissues (cotyledon and hypocotyl) and different types of polylactic acid (PLA) microvessels on plant production were evaluated. Cotyledon-derived callus induction increased by 30-60% in all tested combinations of TDZ and NAA concentrations compared the absence of PGRs. Hypocotyl-derived callus induction was improved in most tested combinations of TDZ and NAA concentrations. Moreover, 100% callus induction from both tissues was achieved with TDZ (1, 2 and 3 mg L -1 ) + NAA (0 mg L -1 ). Bud induction from cotyledon tissues was improved with TDZ (1 and 3 mg L -1 ) + NAA (0 mg L -1 ) and from hypocotyl with TDZ (1 and 2 mg L -1 ) + NAA (0 mg L -1 ). Shoot elongation from cotyledon tissues was not improved from any combination of PGRs, whereas TDZ (1 mg L -1 ) + NAA (0 mg L -1 ), TDZ (1 mg L -1 ) + NAA (4 mg L -1 ), TDZ (2 mg L -1 ) + NAA (4 mg L -1 ) and TDZ (3 mg L -1 ) + NAA (2 mg L -1 ) improved shoot elongation from hypocotyl tissues. Adventitious rooting and acclimatization of microcuttings ranged from 40 to 70% in three of the tested microvessels. The acclimatized microcuttings had low genetic variability. Successful production of E. microcorys microplants was achieved in this study using hypocotyl tissue and cultivated a culture medium supplemented with TDZ and NAA, using PLA-based microvessels., Competing Interests: Conflict of interestOn behalf of all authors, the corresponding author states that there is no conflict of interest., (© King Abdulaziz City for Science and Technology 2021.)

This study aimed to analyze the physical properties of the seeds of Moquiniastrum polymorphum when processed by mini-SAS, X-ray and seed blower systems. The seeds were purchased from Seeds Caiçara, located in Penápolis-SP. After purchase, the seed lot was characterized by standard tests. In the X-ray test the seeds were classified according to their internal morphology as filled, unfilled or malformed. The seed blower was set at six opening settings, resulting in light and heavy fractions. The evaluations were performed by weighing the seeds that remained in the blower (heavy fraction) and by the amount of filled seeds indicated by the X-ray test. The germination tests were composed of four replicates of 50 seeds. The mini-SAS was used for external evaluation. It was concluded that the combined use of the seed blower and the X-ray test was efficient for the evaluation and determination of the physical quality of the seeds of M. polymorphum. The seed blower at opening settings 5 resulted in the best lot quality. The external parameters were not able to qualitatively evaluate the seeds of M. polymorphum.